/* Copyright 2018 Canaan Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
/**
 * \file cipher.c
 *
 * \brief Generic cipher wrapper for mbed TLS
 *
 * \author Adriaan de Jong <dejong@fox-it.com>
 *
 *  Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
 *  SPDX-License-Identifier: Apache-2.0
 *
 *  Licensed under the Apache License, Version 2.0 (the "License"); you may
 *  not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *  http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *
 *  This file is part of mbed TLS (https://tls.mbed.org)
 */

#include <stdio.h>

#if !defined(MBEDTLS_CONFIG_FILE)

#include "config.h"

#else
#include MBEDTLS_CONFIG_FILE
#endif

#if defined(MBEDTLS_CIPHER_C)

#include "cipher.h"
#include "cipher_internal.h"

#include <string.h>

//#include "utils.h"

#if defined(MBEDTLS_GCM_C)

#include "gcm.h"

#endif

#if defined(MBEDTLS_CCM_C)

#include "ccm.h"

#endif

#if defined(MBEDTLS_ARC4_C) || defined(MBEDTLS_CIPHER_NULL_CIPHER)
#define MBEDTLS_CIPHER_MODE_STREAM
#endif

/* Implementation that should never be optimized out by the compiler */
static void mbedtls_zeroize(void* v, size_t n)
{
    volatile unsigned char* p = v;

    while (n--)
        *p++ = 0;
}

static int supported_init;

const int* mbedtls_cipher_list(void)
{
    const mbedtls_cipher_definition_t* def;
    int* type;

    if (!supported_init)
    {
        def = mbedtls_cipher_definitions;
        type = mbedtls_cipher_supported;

        while (def->type != 0)
            *type++ = (*def++).type;

        *type = 0;

        supported_init = 1;
    }

    return (mbedtls_cipher_supported);
}

const mbedtls_cipher_info_t* mbedtls_cipher_info_from_type(const mbedtls_cipher_type_t cipher_type)
{
    const mbedtls_cipher_definition_t* def;

    for (def = mbedtls_cipher_definitions; def->info != NULL; def++)
        if (def->type == cipher_type)
            return (def->info);

    return NULL;
}

const mbedtls_cipher_info_t* mbedtls_cipher_info_from_string(const char* cipher_name)
{
    const mbedtls_cipher_definition_t* def;

    if (cipher_name == NULL)
        return NULL;

    for (def = mbedtls_cipher_definitions; def->info != NULL; def++)
        if (!strcmp(def->info->name, cipher_name))
            return (def->info);

    return NULL;
}

const mbedtls_cipher_info_t* mbedtls_cipher_info_from_values(const mbedtls_cipher_id_t cipher_id,
    int key_bitlen,
    const mbedtls_cipher_mode_t mode)
{
    const mbedtls_cipher_definition_t* def;

    for (def = mbedtls_cipher_definitions; def->info != NULL; def++)
    {
        if (def->info->base->cipher == cipher_id && def->info->key_bitlen == (unsigned int)key_bitlen && def->info->mode == mode)
            return (def->info);
    }

    return NULL;
}

void mbedtls_cipher_init(mbedtls_cipher_context_t* ctx)
{
    memset(ctx, 0, sizeof(mbedtls_cipher_context_t));
}

void mbedtls_cipher_free(mbedtls_cipher_context_t* ctx)
{
    if (ctx == NULL)
        return;

    if (ctx->cipher_ctx)
        ctx->cipher_info->base->ctx_free_func(ctx->cipher_ctx);

    mbedtls_zeroize(ctx, sizeof(mbedtls_cipher_context_t));
}

int mbedtls_cipher_setup(mbedtls_cipher_context_t* ctx, const mbedtls_cipher_info_t* cipher_info)
{
    if (NULL == cipher_info || NULL == ctx)
        return MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA;

    memset(ctx, 0, sizeof(mbedtls_cipher_context_t));
    ctx->cipher_ctx = cipher_info->base->ctx_alloc_func();
    if (ctx == NULL)
        return (MBEDTLS_ERR_CIPHER_ALLOC_FAILED);

    ctx->cipher_info = cipher_info;

#if defined(MBEDTLS_CIPHER_MODE_WITH_PADDING)
    /*
	 * Ignore possible errors caused by a cipher mode that doesn't use padding
	 */
#if defined(MBEDTLS_CIPHER_PADDING_PKCS7)
    (void)mbedtls_cipher_set_padding_mode(ctx, MBEDTLS_PADDING_PKCS7);
#else
    (void)mbedtls_cipher_set_padding_mode(ctx, MBEDTLS_PADDING_NONE);
#endif
#endif /* MBEDTLS_CIPHER_MODE_WITH_PADDING */

    return 0;
}

int mbedtls_cipher_setkey(mbedtls_cipher_context_t* ctx, const unsigned char* key,
    int key_bitlen, const mbedtls_operation_t operation)
{
    if (NULL == ctx || NULL == ctx->cipher_info)
        return MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA;

    if ((ctx->cipher_info->flags & MBEDTLS_CIPHER_VARIABLE_KEY_LEN) == 0 && (int)ctx->cipher_info->key_bitlen != key_bitlen)
    {
        return MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA;
    }

    ctx->key_bitlen = key_bitlen;
    ctx->operation = operation;

    /*
	 * For CFB and CTR mode always use the encryption key schedule
	 */
    if (operation == MBEDTLS_ENCRYPT || ctx->cipher_info->mode == MBEDTLS_MODE_CFB || ctx->cipher_info->mode == MBEDTLS_MODE_CTR)
        return ctx->cipher_info->base->setkey_enc_func(ctx->cipher_ctx, key,
            ctx->key_bitlen);

    if (operation == MBEDTLS_DECRYPT)
        return ctx->cipher_info->base->setkey_dec_func(ctx->cipher_ctx, key,
            ctx->key_bitlen);

    return MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA;
}

int mbedtls_cipher_set_iv(mbedtls_cipher_context_t* ctx,
    const unsigned char* iv, size_t iv_len)
{
    size_t actual_iv_size;

    if (NULL == ctx || NULL == ctx->cipher_info || NULL == iv)
        return MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA;

    /* avoid buffer overflow in ctx->iv */
    if (iv_len > MBEDTLS_MAX_IV_LENGTH)
        return MBEDTLS_ERR_CIPHER_FEATURE_UNAVAILABLE;

    if ((ctx->cipher_info->flags & MBEDTLS_CIPHER_VARIABLE_IV_LEN) != 0)
        actual_iv_size = iv_len;
    else
    {
        actual_iv_size = ctx->cipher_info->iv_size;

        /* avoid reading past the end of input buffer */
        if (actual_iv_size > iv_len)
            return MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA;
    }

    memcpy(ctx->iv, iv, actual_iv_size);
    ctx->iv_size = actual_iv_size;

    return 0;
}

int mbedtls_cipher_reset(mbedtls_cipher_context_t* ctx)
{
    if (NULL == ctx || NULL == ctx->cipher_info)
        return MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA;

    ctx->unprocessed_len = 0;

    return 0;
}

#if defined(MBEDTLS_GCM_C)

int mbedtls_cipher_update_ad(mbedtls_cipher_context_t* ctx,
    const unsigned char* ad, size_t ad_len)
{
    if (NULL == ctx || NULL == ctx->cipher_info)
        return MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA;

    if (ctx->cipher_info->mode == MBEDTLS_MODE_GCM)
    {
        return mbedtls_gcm_starts((mbedtls_gcm_context*)ctx->cipher_ctx, ctx->operation,
            ctx->iv, ctx->iv_size, ad, ad_len);
    }

    return 0;
}

#endif /* MBEDTLS_GCM_C */

int mbedtls_cipher_update(mbedtls_cipher_context_t* ctx, const unsigned char* input,
    size_t ilen, unsigned char* output, size_t* olen)
{
    int ret;

    if (NULL == ctx || NULL == ctx->cipher_info || NULL == olen)
    {
        printf("bad cipher_info!!");
        return MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA;
    }

    *olen = 0;

    if (ctx->cipher_info->mode == MBEDTLS_MODE_ECB)
    {
        if (ilen != mbedtls_cipher_get_block_size(ctx))
        {
            printf("bb\n");
            return MBEDTLS_ERR_CIPHER_FULL_BLOCK_EXPECTED;
        }

        *olen = ilen;
        ret = ctx->cipher_info->base->ecb_func(ctx->cipher_ctx,
            ctx->operation, input, output);
        if (ret != 0)
        {
            printf("cc\n");
            return ret;
        }

        return 0;
    }

#if defined(MBEDTLS_GCM_C)
    if (ctx->cipher_info->mode == MBEDTLS_MODE_GCM)
    {
        *olen = ilen;
        return mbedtls_gcm_update((mbedtls_gcm_context*)ctx->cipher_ctx, ilen, input,
            output);
    }
#endif

    if (input == output && (ctx->unprocessed_len != 0 || ilen % mbedtls_cipher_get_block_size(ctx)))
    {
        return MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA;
    }
#if defined(MBEDTLS_CIPHER_MODE_CBC)
    if (ctx->cipher_info->mode == MBEDTLS_MODE_CBC)
    {
        size_t copy_len = 0;

        /*
		 * If there is not enough data for a full block, cache it.
		 */
        if ((ctx->operation == MBEDTLS_DECRYPT && ilen + ctx->unprocessed_len <= mbedtls_cipher_get_block_size(ctx)) || (ctx->operation == MBEDTLS_ENCRYPT && ilen + ctx->unprocessed_len < mbedtls_cipher_get_block_size(ctx)))
        {
            memcpy(&(ctx->unprocessed_data[ctx->unprocessed_len]), input,
                ilen);

            ctx->unprocessed_len += ilen;
            return 0;
        }

        /*
		 * Process cached data first
		 */
        if (ctx->unprocessed_len != 0)
        {
            copy_len = mbedtls_cipher_get_block_size(ctx) - ctx->unprocessed_len;

            memcpy(&(ctx->unprocessed_data[ctx->unprocessed_len]), input,
                copy_len);
            ret = ctx->cipher_info->base->cbc_func(ctx->cipher_ctx,
                ctx->operation, mbedtls_cipher_get_block_size(ctx),
                ctx->iv,
                ctx->unprocessed_data, output);
            if (ret != 0)
                return ret;

            *olen += mbedtls_cipher_get_block_size(ctx);
            output += mbedtls_cipher_get_block_size(ctx);
            ctx->unprocessed_len = 0;

            input += copy_len;
            ilen -= copy_len;
        }

        /*
		 * Cache final, incomplete block
		 */
        if (ilen != 0)
        {
            copy_len = ilen % mbedtls_cipher_get_block_size(ctx);
            if (copy_len == 0 && ctx->operation == MBEDTLS_DECRYPT)
                copy_len = mbedtls_cipher_get_block_size(ctx);

            memcpy(ctx->unprocessed_data, &(input[ilen - copy_len]),
                copy_len);

            ctx->unprocessed_len += copy_len;
            ilen -= copy_len;
        }

        /*
		 * Process remaining full blocks
		 */
        if (ilen)
        {
            ret = ctx->cipher_info->base->cbc_func(ctx->cipher_ctx,
                ctx->operation, ilen, ctx->iv, input, output);
            if (ret != 0)
                return ret;

            *olen += ilen;
        }

        return 0;
    }
#endif /* MBEDTLS_CIPHER_MODE_CBC */

#if defined(MBEDTLS_CIPHER_MODE_CFB)
    if (ctx->cipher_info->mode == MBEDTLS_MODE_CFB)
    {
        ret = ctx->cipher_info->base->cfb_func(ctx->cipher_ctx,
            ctx->operation, ilen, &ctx->unprocessed_len, ctx->iv,
            input, output);
        if (ret != 0)
            return ret;

        *olen = ilen;

        return 0;
    }
#endif /* MBEDTLS_CIPHER_MODE_CFB */

#if defined(MBEDTLS_CIPHER_MODE_CTR)
    if (ctx->cipher_info->mode == MBEDTLS_MODE_CTR)
    {
        ret = ctx->cipher_info->base->ctr_func(ctx->cipher_ctx,
            ilen, &ctx->unprocessed_len, ctx->iv,
            ctx->unprocessed_data, input, output);
        if (ret != 0)
            return ret;

        *olen = ilen;

        return 0;
    }
#endif /* MBEDTLS_CIPHER_MODE_CTR */

#if defined(MBEDTLS_CIPHER_MODE_STREAM)
    if (ctx->cipher_info->mode == MBEDTLS_MODE_STREAM)
    {
        ret = ctx->cipher_info->base->stream_func(ctx->cipher_ctx,
            ilen, input, output);
        if (ret != 0)
            return ret;

        *olen = ilen;

        return 0;
    }
#endif /* MBEDTLS_CIPHER_MODE_STREAM */

    return (MBEDTLS_ERR_CIPHER_FEATURE_UNAVAILABLE);
}

#if defined(MBEDTLS_CIPHER_MODE_WITH_PADDING)
#if defined(MBEDTLS_CIPHER_PADDING_PKCS7)

/*
 * PKCS7 (and PKCS5) padding: fill with ll bytes, with ll = padding_len
 */
static void add_pkcs_padding(unsigned char* output, size_t output_len,
    size_t data_len)
{
    size_t padding_len = output_len - data_len;
    unsigned char i;

    for (i = 0; i < padding_len; i++)
        output[data_len + i] = (unsigned char)padding_len;
}

static int get_pkcs_padding(unsigned char* input, size_t input_len,
    size_t* data_len)
{
    size_t i, pad_idx;
    unsigned char padding_len, bad = 0;

    if (NULL == input || NULL == data_len)
        return MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA;

    padding_len = input[input_len - 1];
    *data_len = input_len - padding_len;

    /* Avoid logical || since it results in a branch */
    bad |= padding_len > input_len;
    bad |= padding_len == 0;

    // The number of bytes checked must be independent of padding_len,
    // so pick input_len, which is usually 8 or 16 (one block)
    pad_idx = input_len - padding_len;
    for (i = 0; i < input_len; i++)
        bad |= (input[i] ^ padding_len) * (i >= pad_idx);

    return (MBEDTLS_ERR_CIPHER_INVALID_PADDING * (bad != 0));
}

#endif /* MBEDTLS_CIPHER_PADDING_PKCS7 */

#if defined(MBEDTLS_CIPHER_PADDING_ONE_AND_ZEROS)

/*
 * One and zeros padding: fill with 80 00 ... 00
 */
static void add_one_and_zeros_padding(unsigned char* output,
    size_t output_len, size_t data_len)
{
    size_t padding_len = output_len - data_len;
    unsigned char i = 0;

    output[data_len] = 0x80;
    for (i = 1; i < padding_len; i++)
        output[data_len + i] = 0x00;
}

static int get_one_and_zeros_padding(unsigned char* input, size_t input_len,
    size_t* data_len)
{
    size_t i;
    unsigned char done = 0, prev_done, bad;

    if (NULL == input || NULL == data_len)
        return MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA;

    bad = 0xFF;
    *data_len = 0;
    for (i = input_len; i > 0; i--)
    {
        prev_done = done;
        done |= (input[i - 1] != 0);
        *data_len |= (i - 1) * (done != prev_done);
        bad &= (input[i - 1] ^ 0x80) | (done == prev_done);
    }

    return (MBEDTLS_ERR_CIPHER_INVALID_PADDING * (bad != 0));
}

#endif /* MBEDTLS_CIPHER_PADDING_ONE_AND_ZEROS */

#if defined(MBEDTLS_CIPHER_PADDING_ZEROS_AND_LEN)

/*
 * Zeros and len padding: fill with 00 ... 00 ll, where ll is padding length
 */
static void add_zeros_and_len_padding(unsigned char* output,
    size_t output_len, size_t data_len)
{
    size_t padding_len = output_len - data_len;
    unsigned char i = 0;

    for (i = 1; i < padding_len; i++)
        output[data_len + i - 1] = 0x00;
    output[output_len - 1] = (unsigned char)padding_len;
}

static int get_zeros_and_len_padding(unsigned char* input, size_t input_len,
    size_t* data_len)
{
    size_t i, pad_idx;
    unsigned char padding_len, bad = 0;

    if (NULL == input || NULL == data_len)
        return MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA;

    padding_len = input[input_len - 1];
    *data_len = input_len - padding_len;

    /* Avoid logical || since it results in a branch */
    bad |= padding_len > input_len;
    bad |= padding_len == 0;

    /* The number of bytes checked must be independent of padding_len */
    pad_idx = input_len - padding_len;
    for (i = 0; i < input_len - 1; i++)
        bad |= input[i] * (i >= pad_idx);

    return (MBEDTLS_ERR_CIPHER_INVALID_PADDING * (bad != 0));
}

#endif /* MBEDTLS_CIPHER_PADDING_ZEROS_AND_LEN */

#if defined(MBEDTLS_CIPHER_PADDING_ZEROS)
/*
 * Zero padding: fill with 00 ... 00
 */
static void add_zeros_padding(unsigned char* output,
    size_t output_len, size_t data_len)
{
    size_t i;

    for (i = data_len; i < output_len; i++)
        output[i] = 0x00;
}

static int get_zeros_padding(unsigned char* input, size_t input_len,
    size_t* data_len)
{
    size_t i;
    unsigned char done = 0, prev_done;

    if (NULL == input || NULL == data_len)
        return (MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA);

    *data_len = 0;
    for (i = input_len; i > 0; i--)
    {
        prev_done = done;
        done |= (input[i - 1] != 0);
        *data_len |= i * (done != prev_done);
    }

    return 0;
}
#endif /* MBEDTLS_CIPHER_PADDING_ZEROS */

/*
 * No padding: don't pad :)
 *
 * There is no add_padding function (check for NULL in mbedtls_cipher_finish)
 * but a trivial get_padding function
 */
static int get_no_padding(unsigned char* input, size_t input_len,
    size_t* data_len)
{
    if (NULL == input || NULL == data_len)
        return MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA;

    *data_len = input_len;

    return 0;
}

#endif /* MBEDTLS_CIPHER_MODE_WITH_PADDING */

int mbedtls_cipher_finish(mbedtls_cipher_context_t* ctx,
    unsigned char* output, size_t* olen)
{
    if (NULL == ctx || NULL == ctx->cipher_info || NULL == olen)
        return MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA;

    *olen = 0;

    if (ctx->cipher_info->mode == MBEDTLS_MODE_CFB || ctx->cipher_info->mode == MBEDTLS_MODE_CTR || ctx->cipher_info->mode == MBEDTLS_MODE_GCM || ctx->cipher_info->mode == MBEDTLS_MODE_STREAM)
    {
        return 0;
    }

    if (ctx->cipher_info->mode == MBEDTLS_MODE_ECB)
    {
        if (ctx->unprocessed_len != 0)
            return MBEDTLS_ERR_CIPHER_FULL_BLOCK_EXPECTED;

        return 0;
    }

#if defined(MBEDTLS_CIPHER_MODE_CBC)
    if (ctx->cipher_info->mode == MBEDTLS_MODE_CBC)
    {
        int ret = 0;

        if (ctx->operation == MBEDTLS_ENCRYPT)
        {
            /* check for 'no padding' mode */
            if (ctx->add_padding == NULL)
            {
                if (ctx->unprocessed_len != 0)
                    return MBEDTLS_ERR_CIPHER_FULL_BLOCK_EXPECTED;

                return 0;
            }

            ctx->add_padding(ctx->unprocessed_data, mbedtls_cipher_get_iv_size(ctx),
                ctx->unprocessed_len);
        }
        else if (mbedtls_cipher_get_block_size(ctx) != ctx->unprocessed_len)
        {
            /*
			 * For decrypt operations, expect a full block,
			 * or an empty block if no padding
			 */
            if (NULL == ctx->add_padding && 0 == ctx->unprocessed_len)
                return 0;

            return MBEDTLS_ERR_CIPHER_FULL_BLOCK_EXPECTED;
        }

        /* cipher block */
        ret = ctx->cipher_info->base->cbc_func(ctx->cipher_ctx,
            ctx->operation, mbedtls_cipher_get_block_size(ctx), ctx->iv,
            ctx->unprocessed_data, output);
        if (ret != 0)
            return ret;

        /* Set output size for decryption */
        if (ctx->operation == MBEDTLS_DECRYPT)
            return ctx->get_padding(output, mbedtls_cipher_get_block_size(ctx),
                olen);

        /* Set output size for encryption */
        *olen = mbedtls_cipher_get_block_size(ctx);
        return 0;
    }
#else
    ((void)output);
#endif /* MBEDTLS_CIPHER_MODE_CBC */

    return (MBEDTLS_ERR_CIPHER_FEATURE_UNAVAILABLE);
}

#if defined(MBEDTLS_CIPHER_MODE_WITH_PADDING)

int mbedtls_cipher_set_padding_mode(mbedtls_cipher_context_t* ctx, mbedtls_cipher_padding_t mode)
{
    if (ctx == NULL || ctx->cipher_info->mode != MBEDTLS_MODE_CBC)
    {
        return MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA;
    }

    switch (mode)
    {
#if defined(MBEDTLS_CIPHER_PADDING_PKCS7)
    case MBEDTLS_PADDING_PKCS7:
        ctx->add_padding = add_pkcs_padding;
        ctx->get_padding = get_pkcs_padding;
        break;
#endif
#if defined(MBEDTLS_CIPHER_PADDING_ONE_AND_ZEROS)
    case MBEDTLS_PADDING_ONE_AND_ZEROS:
        ctx->add_padding = add_one_and_zeros_padding;
        ctx->get_padding = get_one_and_zeros_padding;
        break;
#endif
#if defined(MBEDTLS_CIPHER_PADDING_ZEROS_AND_LEN)
    case MBEDTLS_PADDING_ZEROS_AND_LEN:
        ctx->add_padding = add_zeros_and_len_padding;
        ctx->get_padding = get_zeros_and_len_padding;
        break;
#endif
#if defined(MBEDTLS_CIPHER_PADDING_ZEROS)
    case MBEDTLS_PADDING_ZEROS:
        ctx->add_padding = add_zeros_padding;
        ctx->get_padding = get_zeros_padding;
        break;
#endif
    case MBEDTLS_PADDING_NONE:
        ctx->add_padding = NULL;
        ctx->get_padding = get_no_padding;
        break;

    default:
        return (MBEDTLS_ERR_CIPHER_FEATURE_UNAVAILABLE);
    }

    return 0;
}

#endif /* MBEDTLS_CIPHER_MODE_WITH_PADDING */

#if defined(MBEDTLS_GCM_C)

int mbedtls_cipher_write_tag(mbedtls_cipher_context_t* ctx,
    unsigned char* tag, size_t tag_len)
{
    if (NULL == ctx || NULL == ctx->cipher_info || NULL == tag)
        return MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA;

    if (ctx->operation != MBEDTLS_ENCRYPT)
        return MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA;

    if (ctx->cipher_info->mode == MBEDTLS_MODE_GCM)
        return mbedtls_gcm_finish((mbedtls_gcm_context*)ctx->cipher_ctx, tag, tag_len);

    return 0;
}

int mbedtls_cipher_check_tag(mbedtls_cipher_context_t* ctx,
    const unsigned char* tag, size_t tag_len)
{
    int ret;

    if (NULL == ctx || NULL == ctx->cipher_info || ctx->operation != MBEDTLS_DECRYPT)
        return MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA;

    if (ctx->cipher_info->mode == MBEDTLS_MODE_GCM)
    {
        unsigned char check_tag[16];
        size_t i;
        int diff;

        if (tag_len > sizeof(check_tag))
            return MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA;
        ret = mbedtls_gcm_finish((mbedtls_gcm_context*)ctx->cipher_ctx,
            check_tag, tag_len);
        if (ret != 0)
            return ret;

        /* Check the tag in "constant-time" */
        for (diff = 0, i = 0; i < tag_len; i++)
            diff |= tag[i] ^ check_tag[i];

        if (diff != 0)
            return MBEDTLS_ERR_CIPHER_AUTH_FAILED;

        return 0;
    }

    return 0;
}

#endif /* MBEDTLS_GCM_C */

/*
 * Packet-oriented wrapper for non-AEAD modes
 */
int mbedtls_cipher_crypt(mbedtls_cipher_context_t* ctx,
    const unsigned char* iv, size_t iv_len,
    const unsigned char* input, size_t ilen,
    unsigned char* output, size_t* olen)
{
    int ret;
    size_t finish_olen;

    ret = mbedtls_cipher_set_iv(ctx, iv, iv_len);
    if (ret != 0)
        return ret;
    ret = mbedtls_cipher_reset(ctx);
    if (ret != 0)
        return ret;
    ret = mbedtls_cipher_update(ctx, input, ilen, output, olen);
    if (ret != 0)
        return ret;
    ret = mbedtls_cipher_finish(ctx, output + *olen, &finish_olen);
    if (ret != 0)
        return ret;

    *olen += finish_olen;

    return 0;
}

#if defined(MBEDTLS_CIPHER_MODE_AEAD)

/*
 * Packet-oriented encryption for AEAD modes
 */
int mbedtls_cipher_auth_encrypt(mbedtls_cipher_context_t* ctx,
    const unsigned char* iv, size_t iv_len,
    const unsigned char* ad, size_t ad_len,
    const unsigned char* input, size_t ilen,
    unsigned char* output, size_t* olen,
    unsigned char* tag, size_t tag_len)
{
#if defined(MBEDTLS_GCM_C)
    if (ctx->cipher_info->mode == MBEDTLS_MODE_GCM)
    {
        *olen = ilen;
        return (mbedtls_gcm_crypt_and_tag(ctx->cipher_ctx, MBEDTLS_GCM_ENCRYPT, ilen,
            iv, iv_len, ad, ad_len, input, output,
            tag_len, tag));
    }
#endif /* MBEDTLS_GCM_C */
#if defined(MBEDTLS_CCM_C)
    if (ctx->cipher_info->mode == MBEDTLS_MODE_CCM)
    {
        *olen = ilen;
        return (mbedtls_ccm_encrypt_and_tag(ctx->cipher_ctx, ilen,
            iv, iv_len, ad, ad_len, input, output,
            tag, tag_len));
    }
#endif /* MBEDTLS_CCM_C */

    return (MBEDTLS_ERR_CIPHER_FEATURE_UNAVAILABLE);
}

/*
 * Packet-oriented decryption for AEAD modes
 */
int mbedtls_cipher_auth_decrypt(mbedtls_cipher_context_t* ctx,
    const unsigned char* iv, size_t iv_len,
    const unsigned char* ad, size_t ad_len,
    const unsigned char* input, size_t ilen,
    unsigned char* output, size_t* olen,
    const unsigned char* tag, size_t tag_len)
{
#if defined(MBEDTLS_GCM_C)
    if (ctx->cipher_info->mode == MBEDTLS_MODE_GCM)
    {
        int ret;

        *olen = ilen;
        ret = mbedtls_gcm_auth_decrypt(ctx->cipher_ctx, ilen,
            iv, iv_len, ad, ad_len,
            tag, tag_len, input, output);

        if (ret == MBEDTLS_ERR_GCM_AUTH_FAILED)
            ret = MBEDTLS_ERR_CIPHER_AUTH_FAILED;

        return ret;
    }
#endif /* MBEDTLS_GCM_C */
#if defined(MBEDTLS_CCM_C)
    if (ctx->cipher_info->mode == MBEDTLS_MODE_CCM)
    {
        int ret;

        *olen = ilen;
        ret = mbedtls_ccm_auth_decrypt(ctx->cipher_ctx, ilen,
            iv, iv_len, ad, ad_len,
            input, output, tag, tag_len);

        if (ret == MBEDTLS_ERR_CCM_AUTH_FAILED)
            ret = MBEDTLS_ERR_CIPHER_AUTH_FAILED;

        return ret;
    }
#endif /* MBEDTLS_CCM_C */

    return (MBEDTLS_ERR_CIPHER_FEATURE_UNAVAILABLE);
}

#endif /* MBEDTLS_CIPHER_MODE_AEAD */

#endif /* MBEDTLS_CIPHER_C */
